stimulus(n = noun.cognition) input, stimulant, stimulation - any stimulating information or event; acts to arouse action;
is a kind of information
has particulars: elicitation, evocation, induction, kick, turn-on, negative stimulation, turnoff, conditioned stimulus, reinforcement, reinforcer, reinforcing stimulus, cue, discriminative stimulus, positive stimulus, negative stimulus
Derived forms verb stimulate₁, verb stimulate₂, verb stimulate₇, verb stimulate₆

1.  A goad; hence, something that rouses the mind or spirits; an incentive; as, the hope of gain is a powerful stimulus to labor and action. [1913 Webster]

2.  That which excites or produces a temporary increase of vital action, either in the whole organism or in any of its parts; especially (Physiol.), any substance or agent capable of evoking the activity of a nerve or irritable muscle, or capable of producing an impression upon a sensory organ or more particularly upon its specific end organ. [1913 Webster]
" Of the stimuli applied to the sensory apparatus, physiologists distinguish two kinds: (a) Homologous stimuli, which act only upon the end organ, and for whose action the sense organs are especially adapted, as the rods and cones of the retina for the vibrations of the either. (b) Heterologous stimuli, which are mechanical, chemical, electrical, etc., and act upon the nervous elements of the sensory apparatus along their entire course, producing, for example, the flash of light beheld when the eye is struck." Landois & Stirling. [1913 Webster]

stimulus, n. (pl. stimuli)
1 a thing that rouses to activity or energy.
2 a stimulating or rousing effect.
3 a thing that evokes a specific functional reaction in an organ or tissue.

Etymology:
L, = goad, spur, incentive

N  motive, springs of action, wellsprings of action, reason, ground, call, principle, by end, by purpose, mainspring, primum mobile, keystone, the why and the wherefore, pro and con, reason why, secret motive, arriere pensee, intention, inducement, consideration, attraction, loadstone, magnet, magnetism, magnetic force, allectation, allective, temptation, enticement, agacerie, allurement, witchery, bewitchment, bewitchery, charm, spell, fascination, blandishment, cajolery, seduction, seducement, honeyed words, voice of the tempter, song of the Sirens forbidden fruit, golden apple, persuasibility, persuasibleness, attractability, impressibility, susceptibility, softness, persuasiveness, attractiveness, tantalization, influence, prompting, dictate, instance, impulse, impulsion, incitement, incitation, press, instigation, provocation, inspiration, persuasion, suasion, encouragement, advocacy, exhortation, advice, solicitation, lobbyism, pull, incentive, stimulus, spur, fillip, whip, goad, ankus, rowel, provocative, whet, dram, bribe, lure, decoy, decoy duck, bait, trail of a red herring, bribery and corruption, sop, sop for Cerberus, prompter, tempter, seducer, seductor, instigator, firebrand, incendiary, Siren, Circe, agent provocateur, lobbyist, impulsive, motive, suasive, suasory, persuasive, persuasory, hortative, hortatory, protreptical, inviting, tempting suasive, suasory, seductive, attractive, fascinating, provocative, induced, disposed, persuadable, spellbound, instinct with, smitten with, infatuated, inspired, by, because, therefore, from this motive, from that motive, for this reason, for that reason, for, by reason of, for the sake of, count of, out of, from, as, forasmuch as, for all the world, on principle, fax mentis incendium gloriae, temptation hath a music for all ears, to beguile many and be beguiled by one.

aversive stimulus, conditioned stimulus, discriminative stimulus, negative reinforcing stimulus, negative stimulus, positive reinforcing stimulus, positive stimulus, reinforcing stimulus, stimulus generalisation, stimulus generalization